Czechoslovak Mathematical Journal, Vol. 71, No. 4, pp. 1015-1023, 2021
A note on classes of structured matrices with elliptical type numerical range
Natália Bebiano, Susana Furtado
Received May 4, 2020. Published online February 3, 2021.
Abstract: We identify new classes of structured matrices whose numerical range is of the elliptical type, that is, an elliptical disk or the convex hull of elliptical disks.
Keywords: tridiagonal matrix; antitridiagonal matrix; elliptical disk; numerical range
Affiliations: Natália Bebiano, Mathematics Center of the University of Coimbra, Mathematics Department, University of Coimbra, 3001-454 Coimbra, Portugal, e-mail: bebiano@mat.uc.pt; Susana Furtado (corresponding author), Center for Functional Analysis, Linear Structures and Applications, Faculty of Economics, University of Porto, Rua Dr. Roberto Frias, 4200-464 Porto Portugal, e-mail: sbf@fep.up.pt